Developmental time course of auditory perception of modulation speech cues

Abstract

Speech contains strong amplitude modulation (AM) and frequency modulation (FM) cues, which are commonly assumed to play an important role in speech identification for adults. We will review recent studies aiming to characterize the development of auditory perception of AM and FM speech cues for 6 and/or 10-month-old infants learning French or Mandarin [e.g., Cabrera, L., Tsao, F.-M., Gnansia, D., Bertoncini, J., & Lorenzi C. (2014), J. Acoust. Soc. Am. 136, 877–882; Cabrera, L., Bertoncini, J., & Lorenzi, C. (2013), J. Speech, Lang., Hearing Res. 56, 1733–1744]. These studies were based on vocoders, which are analysis and synthesis systems designed to manipulate the modulation components of speech sounds in a given number of frequency bands. Overall, the results suggest that: (i) the auditory processing of AM and FM speech cues is “functional” by 6 months, (ii) the auditory processing of the AM and FM cues is fine-tuned by language exposure between 6 and 10 months. These findings may help improving current models of modulation processing that do not take into account the plasticity of the auditory and speech-processing system.